Roller chain inner plate

ABSTRACT

A bicycle chain is used to transmit the drive force to at least one chain wheel and contains chain rollers and inner and outer plates which are connected to each other by means of pins. As a result of a corresponding shaping of the extremely hard inner plate, the wear on the teeth which cooperate with the inner plate can be reduced on the chain wheels or sprockets.

This application claims priority to, and/or the benefit of, Germanpatent application DE 10 2015 011 500.6, filed on Sep. 9, 2015, andGerman patent application DE 10 2016 009 814.7, filed on Aug. 12, 2016.

FIELD OF THE INVENTION

The present invention relates generally to a drive chain for bicycleswith improved wear behavior, and specifically to a drive chain thatcooperates with multiple sprockets on a rear wheel.

BACKGROUND

Drive chains for bicycles with a derailleur system are composed of chainlinks which are arranged so as to be able to he pivoted with respect toeach other and by means of which a closed chain loop is formed for driveforce transmission. These chain links can be rotated relative to eachother about chain pins, wherein the chain pins are received by holeswhich are located centrally in the two round end regions of each chainplate. The two end regions of each chain plate are connected to eachother by means of a connection region with an outer contour which is inmost cases constructed in a tapered manner. The chain links have eithera pair of inner plates or a pair of outer plates. The inner plates haveat their inner side collars, wherein a chain roller is rotatablyarranged on a pair of collars which are arranged in a mirror-symmetricalmanner relative to each other, respectively. The teeth of the chainwheels can engage in the intermediate spaces between the plate pairs.

This engagement operation takes place both in the case of a drivingoperation, in which the chain moves into engagement with teeth on asingle chain wheel, and when the chain is displaced when switching fromone chain wheel to the adjacent chain wheel. In order to carry out theseengagement functions, it is desirable to construct the intermediatespaces between the plate pairs to be as large as possible in thedirection perpendicular to the inner side of the plates. On the innerplates which are located more closely relative to each other, chamfershelp to form an introduction funnel-like member for the teeth of thechain wheel being introduced into the intermediate spaces.

In the development of derailleur systems for bicycles which comprise afront chain wheel, roller chain, multiple rear sprockets and associatedshifting devices, the number of sprockets on the multiple sprocketarrangement has continuously increased in a gradual manner. This hasinvolved changes of the dimensions of sprockets, chain plates, chainpins and chain rollers, primarily the dimensions in the directionparallel to the longitudinal axis of the chain pins. Consequently, thechain is adapted to the rear sprockets which are positioned on the rearwheel hub with increasingly small axial spacing with respect to eachother. In this instance, it is clear that the components of the chainwhich protrude in an axial direction beyond the outer side of the chainare also obstructive since they can come into contact with components ofthe adjacent sprocket in an undesirable and disruptive manner.

A reduction of the dimensions of the components of the chain leads inthis instance to an increase of the loads for the chain, for example,the surface pressure on the chain pins which have become shorter. Thisresults in an increase of the wear which is counteracted, for example,with the use of harder materials or by the provision of a morewear-resistant surface coating or by means of hardening of the surface.

The single-sided increase of the surface hardness of the chaincomponents in the chain/chain wheel system at the side of the chainalone leads in this instance to a more rapid wear at the side of thechain wheels or the sprockets.

EP 1 527 490 A2 sets out chamfers in the direction towards the outercontour of the plates which arc intended to reduce the generation ofnoise when the sprocket teeth leave the intermediate plate spaces. It isdescribed that noise is produced when the tooth tip or an edge on thetooth tip slides over edges on the outer contour of the chain plates.This sliding takes place when the chain plate and sprocket tooth moveout of engagement during normal driving operation without any gearchange with the chain which extends in an oblique manner away from themultiple sprocket assembly and also during gear change operation whenthe change portion of the chain which extends from one chain wheel tothe adjacent chain wheel moves in a radially outward direction away fromthe tooth arrangement. This takes place when the change portion of thechain is moved in from the rear sprocket into the tensioned strand ofthe chain and when the change portion of the chain is moved from thefront chain wheel into the slack strand of the chain.

This approach for reducing noise has also been implemented in thestructural solutions which are set out in DE 10 2014 215 928 and in DE10 2014 215 960.

The patent application U.S. Pat. No. 4,642,078 sets out a drive chainwhich is constructed in a particularly narrow manner and which issuitable for a multiple sprocket assembly on a rear wheel hub with ahigh number of gears. The drive chain set out has protruding innerplates and planar outer plates.

The inner side of the connection region of the inner plates has incomparison with the contact face between the chain roller and inner sideof the inner plate an offset in outward direction which, when thematerial thickness of the inner plate is retained, also appears on theouter side on the connection region of the inner plates. Starting fromthe outer contour of the connection region of the inner plates, there isan outward protuberance which forms a funnel-like opening for theintroduction of the teeth of the sprocket or chain wheel. The clearwidth between the plates of the inner plate pair is on the wholeincreased by the offset mentioned. Consequently, favorable conditionshave been provided for the introduction of a tooth into the inner plateintermediate space.

In EP 2 535 616 the solution from U.S. Pat. No. 4,642,078 has beendeveloped by the outer side on the connection region of the inner platebeing constructed in a planar manner. There is consequently produced atthe connection region of the inner plate a smaller material thickness incomparison with the round end regions of the inner plate. A reducedmaterial thickness at the connection region of the inner plate has alsoalready been implemented in DE 197 05 018.

With multiple sprocket assemblies having a further increased the numberof sprockets, it is consequently necessary to take measures to obtain orachieve a reliable engagement of the sprocket teeth in the intermediatespace between a pair of inner plates. These measures include thereduction of the dimensions, for example, a shortening of the length ofchain pins and chain rollers which leads to an increase of the componentloads and to increased wear.

SUMMARY AND DESCRIPTION

In an embodiment, a chain inner plate for a roller chain has an innerside, an outer side, two ends having, annular regions, each annularregion having a round outer contour, a connection region, which connectsthe two annular regions, and two collars, of which one collar isarranged at the inner side directly adjacent to each of the two annularregions. The connection region of the inner side has a recess having aninner side material thickness and the inner side material thickness issmaller than an annular region material thickness of the annularregions. A surface of the recess comprises a first curved part-face,wherein a part-face may be a sliding surface, which adjoins a planarpart-face, or a second curved part-face having at least one tangentialtransition when viewed in cross-section.

In an embodiment, a roller chain for a bicycle contains outer plates,chain pins, chain rollers and chain inner plates. At least one chaininner plate has an inner side and an outer side, two ends having annularregions which each have a round outer contour, a connection region,which connects two annular regions, and two collars, of which one collaris arranged at the inner side directly adjacent to each of the twoannular regions. The connection region of the inner side has a recesshaving an inner side material thickness, which is smaller than anannular region material thickness of the annular regions. A surface ofthe recess has a first curved part-face which adjoins a planarpart-face; or a second curved part-face having at least one tangentialtransition when viewed, in cross-section.

In an embodiment, a chain inner plate for a roller chain has an innerplate inner side and an inner plate outer side, two ends having twoannular regions which each have a round outer contour, and a hole whichis substantially concentric with respect to the outer contour, aconnection region, which connects the two annular regions, and twocollars, of which in each case one collar is arranged at the inner sidedirectly adjacent to in each case one of the two annular regions. Aninner plate catch chamfer is provided between the round outer contour ofthe annular region and the annular region on the inner plate inner side,and wherein the inner plate catch chamfer encloses a chamfer angle ofless than forty-five (45) degrees with the inner plate inner side of theannular region.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the outer side of an outer plate;

FIG. 2 shows the inner side of an outer plate;

FIG. 3 shows the outer side of an inner plate;

FIG. 4 shows the inner side of an inner plate;

FIG. 5 shows a chain portion with inner and outer plates;

FIG. 6 shows a cut-out of a chain and chain wheel during the switchingoperation;

FIG. 7 is a perspective view of an inner plate of a roller chainaccording to an embodiment when viewed from the inner side of the chain;

FIG. 8 shows the inner side of an inner plate of a roller chainaccording to at embodiment when viewed in a direction parallel to thecenter axes of the holes in the end regions;

FIG. 9 is a sectioned view with a section in accordance with the line“A-A” in FIG. 8, which extends transversely through the connectionregion;

FIG. 10 is a sectioned view with a section in accordance with the line“B-B” in FIG. 8, which corresponds to the plane of symmetry in thelongitudinal direction and through which two center axes of the holesextend;

FIG. 11 is a cross-section of an embodiment through the center axis of achain pin of the roller chain with a continuously hollow pin, and with acomparison of the shape of the pin ends before and after the shapingoperation using a planar tool;

FIG. 12 shows the chamfer according to an embodiment on the inner sideof the inner plate, which has a chamfer angle of less than forty-five(45) degrees; and

FIG. 13 shows the chamfer on the inner side of the inner plate accordingto the embodiment of FIG. 12.

DETAILED DESCRIPTION OF THE DRAWINGS

A roller chain is provided for multiple sprocket assemblies having anincreased number of sprockets. The roller chain provides a reliableengagement of the sprocket teeth in the intermediate space between apair of inner plates and furthermore to keep the anticipated higherlevel of wear within limits. In an embodiment, it is possible for nocomponents of the ends of the chain pins to protrude beyond the outerside of the outer plates and to provide starting points for anundesirable contact between the pin end and the sprocket tooth on theadjacent sprocket.

An engagement of the sprocket teeth into the intermediate space betweena pair of inner plates takes place in the case of the outer plate chainlinks, in which a pair of outer plates produces the connection betweenchain pins which are adjacent in the chain longitudinal direction.There, the inner plates, which protrude beyond the chain rollers,interact with the sprocket teeth, albeit only when the respectivesprocket tooth has already moved with its outer contour radially farinto the intermediate space between the chain links and has moved intothe vicinity of the corresponding chain roller.

Here, contact occurs between the inner plates and sprocket tooth. Saidcontact inevitably leads to wear, primarily of the sprocket tooth, thematerial of which is generally softer than the material of the chainplates.

Said wear increases if the chain running onto or off the sprocketassumes a greater angle of obliquity in relation to the plane of thechain wheel.

The bevels and chamfers on the inner plates of the chain plates areprovided in order that the sprocket tooth and chain enter intoengagement in an effective manner; said bevels and chamfers formfunnel-like “passages” on the chain for the entry and exit of the toothtips.

Said “passages” are effective both when the chain is displaced from therelatively small sprocket to the relatively large sprocket and when thechain is displaced from the relatively large sprocket to the relativelysmall sprocket. The structural design of said passages plays a majorrole with regard to wear.

In an embodiment, the bevels and chamfers go far beyond that which isknown as a chamfer at an angle of forty-five (45) degrees for breakingup a sharp edge on a solid part or on a sheet-metal part such as a chainplate.

For a changeover of the chain from the relatively small sprocket to therelatively large sprocket for the purposes of changing gear, radiallyinclined bevels are provided on the teeth on the relatively largesprocket, by way of the action of which bevels the chain repeatedlyslides on said teeth of the rotating, relatively large sprocket andcannot be displaced axially toward the relatively large sprocket. Saidbevels are thus a reliable feature for switching assistance in order toprevent a displacement, which is undesired at certain circumferentialpositions, of the chain links in a direction parallel to the axis ofrotation of the sprocket toward the relatively large sprocket.

In the event of a changeover from the relatively large sprocket to therelatively small sprocket, such a reliable feature for switchingassistance does not exist. Rather, the chain links can pass out ofengagement at any circumferential position on the relatively largesprocket if, during a switching process, the diverting forces impartedby the rear chain switching mechanism are merely great enough.

Thus, further starting points for a further development of the rollerchains for bicycles emerge from the ever-increasing demands with regardto the switching from a relatively large sprocket to a relatively smallsprocket at the rear wheel of the bicycle. In particular, it is soughthere to make it possible for said switch to be performed in controlledfashion only at certain circumferential positions on the relativelylarge sprocket at which the changing-over chain can, at the relativelysmall sprocket, too, immediately engage into the sprocket teeth withoutfirst running over the tooth tips on the relatively small sprocket.

For this purpose, on selected teeth on the relatively large sprocket,bevels which may be inclined in the circumferential direction areprovided in order to permit a passage of an inner plate link laterallypast said tooth, as presented in DE 4330989.

As a further means for avoiding a tendency of disengagement of the chainfrom the relatively large sprocket, it has proven to be effective forthe sprocket teeth to be formed with a greater thickness, which almostcompletely fill the intermediate space between a pair of inner plates.Thus, the possibility of the chain links being displaced transverselywith respect to the sprocket teeth in a direction parallel to the axisof the chain pin is reduced. Said measure is supplemented by the use ofa chain in which the inner plates protrude in relation to the chainrollers. Said aspect is discussed in EP 2 141 069.

Altogether, said chamfers on the inner sides of the chain plates, onwhich in the case of modern chains there is also situated a collar as abearing base for the chain roller, have to satisfy mutuallycontradictory conditions.

Firstly, the height of the chamfer extending in a radial directionshould be small in order that the inner side, protruding beyond thechain roller, of the inner plate is available up to as great as possiblea radial height for the guidance between sprocket tooth and chain innerplate. This yields a demand for a large chamfer angle between thechamfer and the plane formed by the inner plate inner side.

Secondly, the chamfer should form a small chamfer angle in order thatthe wear remains low. According to the invention, a chamfer angle hasbeen selected which yields a low level of wear.

FIGS. 1 to 6 show details of a known chain which show the environmentfor the use of the inner plate or which are also used with the innerplate for a roller chain.

FIG. 1 shows the outer plate outer side 5 of an outer plate 1 with aconnection region 2 and two annular regions 7. The connection region 2optionally protrudes outwards. In order to receive the chain pins 18which are not illustrated, each annular region 7 has a hole 3 which isprovided in each case with a pin end embossing 4. Each of the pin endembossings 4 has an outwardly funnel-shaped expansion in which athickened pin end which is not shown can be received in apositive-locking manner.

The contour of the outer plate 1 is rounded and is formed by concaveedge portions 6 on the connection region 2 and convex edge portions 41on the annular regions 7. The convex edge portions 41 are provided inFIG. 1 at the top right and bottom left with an outer plate deflectionchamfer 8, respectively, which extend over an angular range ofapproximately ninety degrees (90°) and terminate upstream a the plateends 9. In the connection region 2 there is located for weight reductionan opening 10 with rounded edges 11 which is provided in the chainaccording to an embodiment.

FIG. 2 shows the inner side of an outer plate 1 with the holes 3 andwith the optional opening 10. The concave edge portions 6 are in eachcase provided with an outer plate catch chamfer 12 which extends in thelongitudinal direction over the connection region 2.

FIG. 3 shows the inner plate outer side 15 with two holes 3 forreceiving chain pins 18 which are not illustrated. The concave edgeportions 6 on the connection portion 2 are provided with relatively wideoptional inner plate deflection chamfers 14. The convex edge portions 41are not chamfered.

FIG. 4 shows the inner plate inner side 31 of an inner plate 13 with thetwo holes 3. These holes 3 are each chamfered with tubular collars 16for receiving the chain rollers 20 which are not shown. The concave edgeportions 6 and convex edge portions 41 have with the exception of theplate end 9 a peripheral inner plate catch chamfer 17.

FIG. 5 shows a chain portion with the outer plates 1 and the innerplates 13. The chain plates are connected to each other in anarticulated manner by means of chain pins 18. The pin ends 19 of thechain pins 18 do not protrude in an axial direction beyond the pin endembossings 4 of the outer plates 1. The outer plates 1 have on the innersides in the connection region 2 outer plate catch chamfers 12 and onthe outer sides outer plate deflection chamfers 8. A chain roller 20 isassociated with each chain pin 18.

The inner plate deflection chamfers 14 ensure that, when the chain isdisplaced onto an adjacent chain wheel, both inner plates laterally passa tooth and do not mount the tooth.

The inner plate catch chamfers 17 on the inner sides of the inner platesserve to form a funnel shape of the largest possible clear width for theengaging teeth. The construction of these inner plate catch chamfers 17is an important component of the inner plates 13.

FIG. 6 shows a portion of the chain 21 and of a larger chain wheel 22during the switching operation from the smaller chain wheel, which isnot illustrated, towards the larger chain wheel 22 which rotates in acounterclockwise direction. The chain change portion 30 extendstangentially away from the smaller chain wheel in the direction towardsthe larger chain wheel 22.

The chain 21 is illustrated as an outer view. The larger chain wheel 22which is schematically illustrated with dot-dash lines may be a frontchain wheel on a crankset or a rear sprocket on the rear wheel.

If the larger chain wheel is a front chain wheel on a crankset, thechain 21 faces the viewer, and the larger chain wheel 22 is locatedtherebehind.

If the larger chain wheel is a rear sprocket on the rear wheel, thelarger chain wheel 22 faces the viewer and the chain 21 is locatedtherebehind.

A deflection tooth 23 with an embossing 42 and a catch tooth 25 can beseen on the larger chain wheel 22.

This view illustrates the function of the outer plate deflection chamfer8 when the chain 21 and rear multiple sprocket assembly cooperate andshows how the outer plate 1 when switching towards the larger chainwheel 22 can slide along the flank of the laterally recessed deflectiontooth 23 in the direction of an embossing edge 24. The outer platedeflection chamfer 8 on the convex edge portion 41 prevents the outerplate 1 from becoming caught with the left lower edge on the laterallynon-recessed tooth base. The non-chamfered right lower edge of the outerplate 1 is intended to be supported on the tooth base of the followingtooth 25 and in this instance to move the chain 21 to the level of thelarger chain wheel 22.

Although the inner plate 13 which is provided with the deflectionchamfer 14 is deflected by the following tooth 25, the subsequent outerplate 1 now moves over the next tooth and consequently successfully endsthis switching operation.

FIG. 7 shows an inner plate 13 according to the invention with the twoannular regions 7 and the tapered connection region 2 which has twoconcave edge portions 6. Centrally in the annular regions 7 there areshown holes 3 which are bordered by collars 16. The peripheralcylindrical outer faces of the collars 16 provide the hearing base forthe chain rollers 20 which arc not illustrated. The outer face 5 (whichcannot be seen) of the inner plate 13 is constructed in a planar manner.

The inner plate is produced from a planar starting material. Theoriginal material thickness occurs only in a radially outward directionadjacent to the collars 16. In the connection region 2, something isremoved from the original material thickness at the inner plate innerside 31.

At the inner plate inner side 31 in the connection region there are aplurality of curved faces which merge into each other. In this instance,a tangential transition between the curved part-faces is particularlyadvantageous since there are then no edges at the transition locations.When teeth, which are not illustrated, are introduced, edges act likesmall cutting edges of a small tool with the tendency to remove materialcomponents from members which slide over this edge.

The separation lines 32 shown in FIG. 7 represent transitions betweenadjacent curved surface regions, but not edges.

With previously known inner plates, complex contours on the inner platewere dispensed with. There were selected simple geometric shapes whichin the production of shaping tools involved lesser requirements andwhich could also be verified in a more effective manner in terms oftheir dimensional accuracy using simple measurement and verificationmeans. These advantages were relinquished in connection with the innerplate 13 according to the invention.

It is also conceivable to modify the described arrangement of completelycurved part-faces 44, 47. It would thus be possible for a firstpart-face 44 which is arranged symmetrically relative to the concaveedge portion 6 to also be constructed as a planar face with an almostinfinite radius of curvature. In another modification, the secondpart-faces 47 which directly adjoin the concave edge portion 6 couldhave in the directions perpendicular to the concave edge portion 6 analmost infinite radius of curvature.

FIG. 8 also shows the inner plate according to the invention, whenviewed parallel to the axes of the cylindrical inner faces inside thecollars.

The section path A-A through the plane of symmetry between the holes 3and the section path B-B through the center axes 34 of the cylindricalinner faces on the collars 16 can be seen.

FIG. 9 is a sectioned view in the section A-A through the plane ofsymmetry between the holes 3.

The outer plate outer face 5 which can be seen at the left is planar.The right edging of the sectioned face which is illustrated in the usualshaded manner is curved, wherein a first curved part-face 44 has alarger radius of curvature or a smaller curvature. The edge regions 43which adjoin it in a tangential transition in an upward direction and ina downward direction have a larger curvature or a smaller radius ofcurvature.

FIG. 10 is a sectioned view with a section B-B through the center axes34 of the cylindrical inner faces on the collars 16.

It can be seen that in the connection region 2 at the inner side 31 ofthe inner plate 13 something has been taken away from the originalmaterial thickness 33, whereby a recess 46 is produced. That is to say,the surface is recessed and a step 38 is produced.

FIG. 11 is a cross-section through the center axis of a chain pin of theroller chain according to the invention with a comparison of the shapingof the pin ends 19 before and after the shaping operation using a flattool 35. In this instance, the dashed line corresponds to the stateprior to the shaping operation.

The chain pin 18 is constructed as a hollow pin with a through-hole 37.In the direction towards the pin ends 19, the wail thickness 36 of thehollow pin decreases as a result of a conical expansion of the hole 37,wherein the outer face of the chain pin 18 is a cylindrical face. Acenter line between the cylindrical outer face of the chain pin 18 onthe one hand and the conical expansion of the hole 37 on the other handis thereby inclined in a radially outward direction with respect to thecenter axis 34 of the hole in the direction towards the pin end 19,whereby the wall in the sectioned view appears to be tilted.

When a force acts parallel to the center axis 34 of the hole 3 as aresult of a flat tool 35 on the pin ends 19, the wall which appearstilted has the tendency to give way radially outwards, accordinglybecome plastically deformed and forming a peripheral projection as astop with respect to a movement of the chain pin relative to the outerplate. Sufficient space is provided for the peripheral projection by achamfer being provided on the outer plate outer side 5 at the outlet ofthe hole 3 and forming a pin end embossing 4.

A similar behavior is already known in the case of a solid chain pinhaving tubular pin ends. In this instance, the solid central portion ofthe chain pin has sufficient rigidity not to become plastically deformedunder the action of the planar tool on the pin ends. Accordingly, it isensured that the chain pins in the solid central portion do not becomedeformed and ultimately a precisely defined spacing is produced betweenthe outer plates. This spacing is decisive for the lateral movabilitybetween the chain links as a result of the play provided between theelements of the chain which are arranged in a row from one pin end tothe other pin end, that is to say, the two outer plates, the two innerplates and the chain roller.

In the case of a chain pin 18 with a through-hole 37, the relationshipsare significantly more complex since the central portion 39 of the pinswhich adjoins the pin ends 19 already has a tendency to becomeplastically deformed under the action of a smaller axial farce from atool 35. The difference, which is only small, with respect to the axialforce required for the shaping of the tubular pin end 19 on the one handand the tubular central portion 39 on the other hand acts counter to thereliable adjustment of the lateral movability described.

However, it has been found that when taking into account or includingthe plastic shortening of the chain pin with a through-hole 37, asoccurs under the action of the tools 35, it may be possible to adjustthe lateral movability of the chain in accordance with requirements. Itis then consequently possible to shape the pin ends by means of planartools 35 in such a manner that they do not protrude beyond the outerplate outer side 5, which is a requirement with sprockets which arearranged in increasingly tight rows in an axial direction.

In this instance, in alternative methods of the shaping operation bymeans of a planar tool 35 can be complemented by means of one or moreadditional process steps in which tools which are constructed in theform of a truncated cone or as a cone are pressed with correspondingforce axially into the hole 37. The cone angles may in this instancehave a value of a different magnitude.

FIG. 12 in conjunction with FIG. 13 shows the inner plate catch chamfer17 on the inner plate inner side 31 in the region of the outer contour45 of the convex edge portion 41, which has a chamfer angle 49 of lessthan forty-five (45) degrees between the inner plate catch chamfer 17and the annular region 7 on the inner plate inner side 31.

A chamfer angle 49 of less than forty-five (45) degrees yieldsparticularly expedient contact forces, and relatively little wearoccurs. This applies both to the entry of the tooth into the spacebetween a pair of outer plates and to the process when the sprockettooth moves out of the plate intermediate space again radially inrelation to the axis of rotation of the sprocket.

During the movement of a sprocket tooth out of the space between a pairof outer plates, there is at least still intermittently contact betweensprocket tooth and inner plate catch chamfer. With increasing obliquityof the running of the chain as a result of the offset, the tendency forcontact to occur between the sprocket tooth and the inner plate catchchamfer 17 increases. Because contact can also be associated with wear,this results in an influence of the obliquity of the running of thechain on the wear on the sprocket tooth.

In an embodiment, a chamfer angle of thirty-eight (38) degrees hasproven to be particularly expedient, wherein the outer contour 45between inner plate catch chamfer 17 and inner plate outer side 15 hasan extension in a direction parallel to the center axis 34 of 0.3millimeters.

1. A chain inner plate for a roller chain, comprising: an inner side; anouter side; two ends having annular regions, each annular region havinga round outer contour; a connection region, which connects the twoannular regions; and two collars, of which one collar is arranged at theinner side directly adjacent to each of the two annular regions; whereinthe connection region of the inner side has a recess having an innerside material thickness, and wherein the inner side material thicknessis smaller than an annular region material thickness of the annularregions; and wherein a surface of the recess comprises a first curvedpart-face which adjoins: a planar part-face, or a second curvedpart-face having at least one tangential transition when viewed incross-section.
 2. The chain inner plate for a roller chain of claim 1,wherein the first curved part-face adjoins the second curved part-facehaving at least one tangential transition when viewed in cross-section.3. The chain inner plate for a roller chain of claim 1, wherein thesurface at the inner side of the annular regions of the connectionregion, the surface at an outer side of the annular regions of theconnection region, and the surface of the collars are speciallyhardened.
 4. The chain inner plate for a roller chain of claim 1,wherein the surface of the recess has a first curved part-face which hasa larger radius of a first curvature and which adjoins a second curvedpart-face with a smaller radius of a second curvature with a tangentialtransition at both sides.
 5. A roller chain for a bicycle, containingouter plates, chain pins, chain rollers and chain inner plates, at leastone chain inner plate comprising: an inner side and an outer side; twoends having annular regions which each have a round outer contour; aconnection region, which connects two annular regions; and two collars,of which one collar is arranged at the inner side directly adjacent toeach of the two annular regions; wherein the connection region of theinner side has a recess having an inner side material thickness, whichis smaller than an annular region material thickness of the annularregions; and wherein a surface of the recess comprises: a first curvedpart-face which adjoins a planar part-face; or a second curved part-facehaving at least one tangential transition when viewed in cross-section.6. The roller chain for a bicycle of claim 5, wherein the chain pinshave pin ends which do not protrude with respect to an outer plate outerside.
 7. The roller chain for a bicycle of claim 6, wherein the pin endsare formed at least in part by a flat tool which applies a force to thepin end in the direction of the center axis of the chain pin in thedirection towards the chain pin, whereby the pin end is shaped so as notto protrude with respect to the outer plate outer side.
 8. A chain innerplate for a roller chain, comprising: an inner plate inner side and aninner plate outer side; two ends having two annular regions which eachhave a round outer contour, and a hole which is substantially concentricwith respect to the outer contour; a connection region, which connectsthe two annular regions; and two collars, of which in each case onecollar is arranged at the inner side directly adjacent to in each caseone of the two annular regions; wherein an inner plate catch chamfer isprovided between the round outer contour of the annular region and theannular region on the inner plate inner side; and wherein the innerplate catch chamfer encloses a chamfer angle of less than 45 degreeswith the inner plate inner side of the annular region.
 9. The chaininner plate for a roller chain according to claim 8, wherein the chamferangle is between 36 and 41 degrees.
 10. The chain inner plate for aroller chain according to claim 9, wherein the chamfer angle is 38degrees.
 11. The chain inner plate for a roller chain according to claim9, wherein the outer contour between inner plate catch chamfer and innerplate outer side has an extension in a direction parallel to the centreaxis of the hole of 0.3 millimeters.